There are no large coronal holes on the Earthside of the sun. Credit: SDO/AIA.

SPACE WEATHERNOAA Forecasts

Updated at: 2011 Oct 25 2200 UTC

FLARE

0-24 hr

24-48 hr

CLASS M

20 %

20 %

CLASS X

01 %

01 %

Geomagnetic Storms:Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm

Updated at: 2011 Oct 25 2200 UTC

Mid-latitudes

0-24 hr

24-48 hr

ACTIVE

15 %

05 %

MINOR

05 %

01 %

SEVERE

01 %

01 %

High latitudes

0-24 hr

24-48 hr

ACTIVE

30 %

10 %

MINOR

15 %

05 %

SEVERE

01 %

01 %

Tuesday, Oct. 25, 2011

What's up in space

Metallic photos of the sun by renowned photographer Greg Piepol bring together the best of art and science. Buy one or a whole set. They make a stellar gift.

AURORAS IN THE USA: A coronal mass ejection (CME) hit Earth on Oct. 24th at approximately 1800 UT (2:00 pm EDT). The impact strongly compressed Earth's magnetic field, directly exposing geosynchronous satellites to solar wind plasma, and sparked an intense geomagnetic storm. As night fell over North America, auroras spilled across the Canadian border into the contiguous United States.

"Wow, wow, wow! These were the best Northern Lights I've seen since 2004," says Shawn Malone, who took this picture from the shores of Lake Superior in Michigan:

"The auroras filled the sky in every direction--even to the south," he says.

Indeed, the display spread all the way down to Arkansas. "When I saw the alert, I ran outside and immediately saw red auroras," reports Brian Emfinger from the city of Ozark. "Within a few minutes the auroras went crazy! It was unbelievable." Update: Emfinger has assembled a 2h 22m time-lapse movie of the display: 29 MB wmv.

THE INSTIGATING EXPLOSION: The CME that hit Earth's magnetic field on Oct. 24th left the sun almost two days earlier. It was propelled in our direction by an unstable magnetic filament, which erupted around 0100 UT on Oct. 22nd. This movie from the Solar and Heliospheric Observatory shows the cloud expanding toward Earth in the first hours after the explosion:

Traveling faster than two million mph, the cloud took about 41 hours to cross the sun-Earth divide. The CME was so geoeffective because it contained a knot of south-pointing magnetic fields. These fields partially cancelled Earth's north-pointing magnetic field at the equator, allowing solar wind plasma to penetrate deeply into Earth's magnetosphere. The rest, as they say in Alabama, is history.

Near Earth Asteroids

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.